A kind of method for preparing ferrous phosphate-based lithium salt material in high-pressure liquid phase

Abstract

The invention discloses a method for preparing a ferrous phosphate-based lithium salt material in a high-pressure liquid phase, comprising: firstly mixing the iron salt solution prepared with an organic reductive weak acid or deionized water and a phosphate-containing raw material, and then mixing the LiOH·H2O was added to the mixed solution and fully stirred with distilled water to form a white emulsion. Method B: first mix the phosphate-containing raw material with LiOH·H2O, then add the iron salt solution prepared with organic reducing weak acid or deionized water, and stir the mixed solution with distilled water to form a white emulsion. Add a conductive agent to the emulsion, adjust the pH value under a protective atmosphere, and seal the reaction; drop to room temperature, filter and precipitate to obtain a powder, and after vacuum baking, the powder is dried at a high temperature under a protective atmosphere to obtain a ferrous phosphate-based lithium salt material . The invention has simple preparation process and no pollution to the environment; the crystallization of the obtained substance is uniform and fine, and the product purity is high; the high-temperature reaction time is short, the temperature is low, the doping is simple and the cost is low, and it has good electrochemical performance.

Description

technical field [0001] The invention relates to the preparation of a lithium ion battery cathode active material, in particular to a preparation method of a lithium ion battery ferrous phosphate-based lithium salt material. Background technique [0002] Since the first lithium-ion battery came out in 1991, its cathode material has been a hot spot in material research. The development of cathode materials has experienced lithium cobaltate and its derivatives, lithium nickelate and its derivatives, lithium manganate and its derivatives, and so on. In recent years, due to the abundance of iron in the earth's crust, its cheap price, and environmental friendliness, based on Fe 2+ / Fe 3+ The substances of redox couples have aroused great interest, so people are racing to study iron-containing lithium salts and their derivatives to replace the current cathode materials. [0003] In 1997, Goodenough et al. synthesized an olivine-type iron-containing lithium salt LiFePO 4 , the s...

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Problems solved by technology

[0003] In 1997, Goodenough et al. synthesized an olivine-type iron-containing lithium salt LiFePO 4 , the structure of the substance is stable, charging and discharging During the process, the volume change of the unit cell is small, and the cycle performance is excellent. Using this material as the positive electrode material of lithium-ion batteries has a high theoretical specific capacity (170mAh / g), which is greater than that of commercial LiCoO 2 The actual capacity performance of 140mAh / g has attracted great attention of researchers. At present, the preparation of this material is not very mature, there are many preparation methods, and the preparation process is still very complicated, especially some solid-phase methods, which are not easy to control. Its crystallization uniformity affects the electrode processing performance of the material and the electrochemical performance of the actual battery

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